The present paper discusses the components of language teachers' awareness, which should differ qualitatively and quantitatively from that of language learners and users. It is argued that especially teachers of English, the European lingua franca, should develop plurilingual awareness to train learners to become multilingual citizens. This awareness involves crosslinguistic, metalinguistic and psycholinguistic knowledge concerning multiple language acquisition. Apart from that, teachers should ideally be multilingual themselves. The paper reports on a survey carried out on over 230 pre-service and in-service Polish teachers of English. It compares their levels of plurilingual awareness relative to their teaching experience, bilingualism/multilingualism factors and the level of L3-Ln languages known. Their awareness seems to be linked with both teaching experience and multilingualism, but it is higher for multilingual teachers proficient in several languages. The paper also presents a qualitative study in the form of a guided interview on a focus group of five in-service teachers. This provides in-depth insight into how they understand plurilingual language teaching. Finally, conclusions are drawn concerning changes in teacher training that would enable teachers to promote plurilingual approaches in class.